Lathe jig for turning crankshafts



June 10, 1952 N, MOSCA 2,599,931

LATHE JIG FOR TURNING CRANKSHAFTS Filed May 28, 1947 2 SHEETS--SHEET l ATTR/VEY June 10, 1952 N MQSCA 2,599,931

LATHE JIG FOR TURNING CRANKSHAFTS Filed May 28, 1947 2 SHEETS--SHEET 2 8? 66- INVENTOR.

NES TOR MOSA ATTORNEY Patented June 10, 1.952

[TED STATES PATE-NT 2,599,931 LATHE JIG Fon TURNING cRANKsHAF'rs NestrMosea, oakland, Calif. Y. .Application-May 2s; 1947, serial No; 751,039

claires. (or. :z2-9) This invention relates to an improved jig for turning axially aligned' bearing surfaces on' the throws of a crankshaft. One objectyof this invention is to provide a jig for lathes which can be used in identical pairs,- for vaccurate truing of the crank-'pinbearing surfaces of a crankshaft.-

Another object-of thisinvention is to provide a jigv which is adjustableV in twoV mutually perpendicular directions so that atrue center can be obtained for eachciank pin on the crankshaft.

Another object of thisinvention is to provide a calibrated jig so that the jigi on one end of the crankshaft can be adjusted toA correspond exactly with-a previously adjusted jig on the other end. Another object of this invention is lto provide a jig which will solve the problem of truing the bearing surfaces on the crank throws of a shaft where usage has caused theY crank pins on the same side of a crankshaftv tor be twisted out of axial alignment with each other. The present device makes it easy to align each bearing surface axially in normal relation' to the piston and connecting rod travel abovet, and independently of what position other crank pins on the same side may require to align them axially' in normal relation to their respective piston and connecting rod travel.

Other objects and advantages of this invention will appear from the course of the following description of an embodiment of this invention. Thisdes'cription is given in accordance with R. S. 4888 and is not intended to li-mit the scope of the` claims to the specific illustrative embodiment. j

In the drawings:

Figli is a View in perspective of a jig embodying Ithis invention;

Fig'.- 2 is a view in elevation showing a crankshaft set in two identical jigs of the type shown in Fig. 1f; y

Fig. 3 is a plan view, partly in section, of the device in Fig. 1

Fig. 4 is a view in section along the line IV-IV in Fig. 3; and 5nis a View in section along the line V-V of Eig. 3.

Fig. 6 is a view in perspective, looking from elow, of a modied form of device embodying my invention;

Figr 7 is a plan view, partly in section, of the device of Fig. 6v;

Fig. 8 is a. view in` section along the line VET- VIII in Fig. 7; and

Fig. 9 is a view looking down on the calibrated 'colla'r' employed in the device shown in Figs. 6 fo' 8, along the line IX-IX in Fig. 7.

Broadly speaking, the jig I0 has a bore for holding one end of the crankshaft rigidly, a, 'fa'ce block with sockets adapted to receive'Y the center pin of a lathe, means t'o move tlie face somewhat wider and 2 1, block in each of two mutually perpendicular directions, and means for securing the face-block inthe positions togwhich it ismoved. Calibrations are provided so that an'identical jig may besecured to each end of the crankshaft and. then setto correspond with each other.

As shown in Fig. 2 a crankshait` l Ican beheld. rigidly in the bearing openings I2r of each jig Iil by a setscrew I3.A (Preferably apiece of lead or some similar material should be placed between the set screw I3 and the crankshaft II to pre- Vent any scoring off the shaft I l by thescrew I3.) Most crankshafts-today haveia face plate I4 at one end to which the flywheel andclutch assembly is bolted. A face plate I4 and stub shaft I5 s used on the right-hand end IE5 of the crankshaft II to provide a bear-ing to fit the bore I2 in the right-handjig.I If the jig ID is constructed as illustrated from a rectangular block of metal and if the two jigs are identical, alignnient of'- the shaft I-I is a very simple'matter.

The face block I1 has several tapered sockets I8 adaptedto V,receive thepointof a lathe center I9. The block` I7 fl-tswithin the opening u2li in the face ofthe jig Iii-'the opening 20 bei-ng longer than the face block Il for reasons which will appear presently. The block I'I is .moved lengthwise in tlfie opening 20 by means of a threaded member 2l having ahead 22 which fits in a recess 23 in alignment with a hole 24 in the end ofthe opening 20'. 4The block I'I has a transverse slot 25 with a special' threaded slide 26 closely tt'ed in Vthe slot 2"5. VThe opening 2T in the end of the block IT has clear` ance on both vsides at 2li to permit lateral shifting of the block 'Il' in relation to the. control member 2 I' which is threaded into the slide piece 26'. The head 22 of th'efrnmbef 2T is recessed to receive an Allen wrench. The block I" is bored out above the head and threaded at 30 to receive a hbll'ow Allen 'set screw 3| which functions to holdthe head `22 of the screw 2l Snug in the recess 23'. A lt 32 looks" lthe set screw 3| in place. A very delicate adjustment is needed in thiskiridY of work and by means of the" above mechanism the face block Il can be moved linearly inside the opening 20 in theV face of the jig I0.

Accurate linear' 'adjustment aloney is 'not sunlcient for a;L jig' for tri'lirig-V a;v crankshaft. There must also be provision for movement of the face block' 'IT in a direction perpendicular to its linear'adjustment just described, so that the axial centerline 33 of the crank pin 34 may be brought into valignment with the axis of the lathecenters I9. To provide for thisl second adjustment, my invention contemplates the use of a pair vof adjacent, sliding, calibrated blocks 35 and' having their opposite faces 31 and38 parallel andv having their contacting faces 39Y and 40 set at an angle longitudinally so that relative longitudinal Imove"- ment of the blocks l35 and 38' will increase yor diminish the distance between the parallel faces 31 and 38. These blocks 35 and 36 are mounted in the jig I in openings adjacent the opening 20 containing the face block I1. The calibrated block 35 is carefully fitted into an opening 4I having parallel ends 42 and 43 which engage the parallel ends 44 and 45 of the block 35. This permits the block 35 to move toward and away from the block I1 but not longitudinally to any noticeable extent. The other block 36 is fitted into an opening 46 having a wall 41 substantially parallel with the face 31 on the block 35. The face 38 of the block 36 bears on this parallel face 41 and there is sufficient end clearance in the opening 46 for the block 36 to be moved longitudinally in relation to the block 35 by the screw 48 which is threaded into the block 36. The screw 48 is mounted in a recess 50 in the jig I0 and has an Allen head I. An Allen set screw 52 and a lock nut 53 hold the screw 43 snug against longitudinal play in the recess 56. As the screw 46 is turned the block 36 moves relatively to the block 35 and the face 31 on the block 35 being in contact with the block I1 moves the latter sideways in the opening 20. The calibrations 54 on the block 35 and the single mark 55 on the block 36 indicate a particular setting which may be used in setting the: blocks on the jig at the other end of the crankshaft. It matters not whether the more calibrations 54 are on one or the other of the blocks 35 and 36.

Also on the block 35 and the block I1 are a set of related calibrations 56 so that the same distance from' the shaft center to the lathe center can be read and the jig on the other end given a similar or related setting.

Any suitable means may be used for holding the block I1 snug against the block 35 and the block 35 against the block 36. In Figs. 3 and 5 this is accomplished by a strong bar spring 58 which is inserted into a longitudinal recess 53 in the jig I6 after the insertion into the opening 66 of a hard metal bearing member 6I. The length of this bearing member 6I should be sufficient to keep the block I1 under substantial pressure for all positions of the moving block 36.

Screws 62 and 63 are used to depress the ends of the spring 58 to bring considerable force against the bearing 6I and therefore against the top of the face block I1 so that it is held rigidly in all of its lateral positions and will move laterally only when the wedge block 36 is moved linearly.

In operation, the crankshaft II has a jig I0 secured to each end as shown in Fig. 2. The

operation planned there is to turn a new surface on the crank pin 34 or 64 or both.

In order to make the calibrations 54 and 56 applicable with reasonable accuracy, the jigs i6 are made with great care, and the sides 65 and 66 of each are parallel and the blocks I1, 36, and 31 in each are spaced in the same distance from the edges. Thus the rst step for each setting of the jigs I0 on the crankshaft II is to lay the jigs I0 on their sides on a known flat surface. When in this position the set screws I3 are tightened on the main bearings 61 of the crankshaft II.

If we start with the jigs I6 on each end of the crankshaft II as shown in Fig. 2 and assume first that the crank pin bearings 34 and 64 are in perfect alignment, the next step is to mount the jigs I0 between the lathe centers I9, selecting a recess I8 in the block I1 which comes closest to aligning the lathe center of the bearings 34 and 64. To get perfect centers I6 with the axial alignment an Allen wrench is inserted into the screw head 22 of the screw 2I and the block I1 on each jig is moved in or out as required to get the correct radial position which Vshould be the same reading on the calibrated scale 56 on each jig. Next the Allen wrench is inserted into the screw 48 and the block 36 in each jig is moved in or out to cause a lateral shifting of the block I1 to bring the lathe center I3 into exact alignment with the axial center 33 of the crank pin bearings 34 and 64. Here again the scale 54 on the blocks 35 and 36 should read alike. These bearings 34 and 64 are then resurfaced. Next the set screws I3 are loosened and the jigs are laid on a flat surface, and the crankshaft is rotated a partial turn to bring the block I1 with its recesses I8 into substantial alignment with another pair of crank pins and the above procedure is repeated. Sometimes after use, the crank arms projecting from the same side of a crankshaft will not be in the same radial plane due to strain, warping or other causes. In such a case the two bearing surfaces 34 and 64 will not necessarily be in axial alignment, and in resurfacing them it is preferable to do each one separately. Each crank pin bearing 34 and 64 should have its axis 33 and 68, respectively, in perfect alignment with the main bearings 61 of the crankshaft II. When this is true the axis of the crank pin bearing will be normal to the path of the connecting rod. Thus in cases where any pair or more of crank pins are not perfectly aligned, as is sometimes found, the setting is made correct for one crank pin bearing at a time, and that bearing is resurfaced at that setting. Usually the other crank pin bearing will have the same radial adjustment and only a small lateral adjustment on each block 35 in each jig will be needed to position it for resurfacing.

The same principles and the same general method of use apply to the modied form of device illustrated in Figs. 6 to 9. The general form of the jig I6 is the same, and the face block I1, on which are the sockets I8, is mounted for movement longitudinally or laterally in the opening 20. The longitudinal movement is controlled by a diierent form of threaded member 16, which is threaded into the block I1; a recess 1I in the face block I1 gives the threaded rod 16 play when the face block I1 is moved laterally by the wedge 35.

The threaded member 1D extends out through the hole 24 in the jig I0 near the opening 20, and bears an integral collar 12 which ts in the base of the recess 23. A collar nut 13 is threaded into the recess 23 over the rod 10 to hold the colar 12 snugly against the end of the recess 23 and is itself looked in place by a lock nut 14. f

The collar 15 which has a calibrated top face 16 is threaded on the rod 10 over the collar nut 13, and is held in place by a set screw. These calibrations can be read against the adjacent edges of the block I0 to enable the operator to know at a glance the position of the block l1 as he adjusts it. Two hexagonal nuts 11 and 18 are subsequently threaded on the rod 10 adjacent the end of the rod 10 and when tightened together serve to lock each other and provide the means by which a wrench can be used to adjust the longitudinal position of the face block I1.

The calibrations 86 on the block I1 are read against the single mark 6I on the wedge block 5, which is in other respects like the block 35 illustrated in Fig. 1. The wedge-shaped block 36 may be constructed in the manner already described in connection with the Fig. 1 type of embodiment, or it may be moved back and forth by a threaded member like the member 10, just described for the block l1.

In the modified form of the invention, the portion 82 of the jig I0 between the edge of the jig and the recess 46 is milled down as illustrated in Fig. 6, and a single calibration mark 83 is placed on it. This is read against the calibrations 84 on the vertical edges of the block 36 to give the longitudinal position of the block 36 and thereby the lateral position of the block I1. The advantage of this modified manner of calibration is that it is better suited to be observed from the side and thus enables the operator to observe the calibrations as he adjusts the device without getting into an unnatural position to do so.

I claim:

l. A lathe jig for supporting an end of a crankshaft in a lathe while resurfacing its crank pin bearing surfaces, including a main body member, two of whose sides lie in planes parallel to each other, said body member also having a hole therein to receive the main bearing of a crankshaft and means for securing said bearing against rotation in said hole, said body member also having an opening one side of which is a guide face parallel to said sides of said body member; a lathe-center-receiving block positioned in said opening; means for holding said block in any selected longitudinal position in said opening, said means including a screw member mounted in one end of said opening and slidably connected to said block; means for holding said block in any selected lateral position in said opening, said latter means including a pair of complementary wedge-shaped pieces positioned so that one bears on one side of said block and the other bears on said guide face and the wedge surfaces bear on each other; means on said body member for limiting one of said pieces to lateral motion; means for moving the other piece along said guide face; and adjustable means on the other side of said block for holding it securely in whatever position it is moved by said wedge means.

2. A lathe jig for supporting an end of a crankshaft in a lathe while resurfacing its crank-pinbearing surfaces comprising a main body member having a hole therein adapted to fit over a main bearing of said crankshaft and means for rigidly mounting said body member in selected positions on said bearing; said body member also having an opening therein, a block mounted in said opening and having a lathe center recess, said block being smaller than said opening; means for holding said block in any desired lengthwise position in said body member, and means for holding said block in any desired sidewise position in said body member, said latter means including a wedge-shaped piece in contact with said block and movable lengthwise in said body member to move said block in one direction and a pressure means to apply a holding pressure on said block from the opposite direction.

3. A lathe jig for supporting an end of a crankshaft in a lathe while resurfacing its crank-pinbearing surfaces comprising a main body member having a hole therein adapted to fit over a main bearing of said crankshaft and means for rigidly mounting said body member in selected positions on said bearing; said body member 6 also having an opening therein, a block mounted in said opening and having a lathe center recess. said block being smaller than said opening;

means for holding said block in any desired lengthwise position in said body member, and means for holding said block in any desired side- Wise position in said body member, said latter means including a pair of complementary wedgeshaped pieces located to one side of said block in the opening in said body member, one piece being in contact with said block and being substantially immobile lengthwise in said opening but mobile crosswise therein, and the other wedge piece being movable lengthwise in said opening; and means for holding said last-named wedge piece at any desired position in its range of travel.

4. A lathe jig for supporting an end of a crankshaft in a lathe while resurfacing its crank-pinbearing surfaces comprising a main body member having a hole therein adapted to fit over a main bearing of said crankshaft and means for rigidly mounting said body member in selected positions on said bearing; said body member also having an opening therein, a block mounted in said opening and having a lathe center recess, said block being smaller than said opening; means for holding said block in any desired lengthwise position in said body member, and means for holding said block in any desired sidewise position in said body member, said latter means including a pair of complementary wedge-shaped pieces located to one side of said block in the opening in said body member, one piece being in contact with said block and being substantially immobile lengthwise in said opening but mobile cross'wise therein, and the other wedge piece being movable lengthwise in said opening, indicia on said block,A

and on said wedge pieces to show the relative positioning of said block to the wedge piece adjacent it and of said wedge pieces relative to each other; and means for holding said last-named wedge piece at any desired position in its range of travel.

5. A crankshaft jig for lathes having means to hold one end of a crankshaft rigidly, a face block having a socket adapted to receive the lathe center of a lathe, and means to move said face block linearly, having in combination therewith a spring to resist movement of said face block in a direction normal to said linear movement, a calibrated block having a plane parallel edge facing said face block and an inclined edge facing in the opposite direction, and a wedge with an index mark movable against said calibrated block to move said face block in a direction normal to said linear movement against the pressure of said spring.

NESTOR MOSCA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 916,646 lAnderson Mar. 30, 1909 1,451,078 `Mantha Apr. 10, 1923 2,111,096 Fritzsch Mar. 15, 1938 2,357,062 Stoll Aug. 29, 1944 FOREIGN PATENTS Number Country Date 18,776 Great Britain of 1898 72,906 Germany Jan. 12, 1894 815,016 France July 5, 1937 

